Justification:
This species is listed as Endangered as its extent of occurrence is less than 5,000 km², the existing range is severely fragmented, and there is a continuing decline in quality of habitat and area of occupancy. Although the situation seems to be improving as wild populations are augmented by captive-bred individuals (1/3 of wild species originated from captive stock), there remain a number of threats to the species in the wild, and the continuation of conservation activities is essential to ensure that the enormous successes seen to date are not undone.

The centre of the range of L. rosalia is the basin of the Rio São João, state of Rio de Janeiro. The original distribution was first clarified by Coimbra-Filho (1969, 1976) and Coimbra-Filho and Mittermeier (1973, 1977). It covered the majority of the lowland coastal region of the state of Rio de Janeiro, below 300 m above sea level. The easternmost record for the species is Mangaratiba, on the coast in the south-east of the state. The original distribution included all or parts of the following municipalities: Mangaratiba, Itaguai, Nova Iguaçú, Nilópolis, São João do Meriti, Duque de Caxias, Rio de Janeiro, Magé, São Gonçalo, Niterói, Itaborai, Maricá, Araruama, Silva Jardim, Saquarema, Rio Bonito, Cachoeiras de Macucu, São Pedro da Aldeia, Cabo Frio, Casimiro de Abreu, Macaé, Conceição de Macabu, Campos, and São João da Barra.

From his surveys carried out between 1962 and 1969, Coimbra-Filho concluded that L. rosalia was extinct in all but seven (Silva Jardim, Cabo Frio, Saquarema, Aruarama, Casimiro de Abreu, Rio Bonito, and São Pedro da Aldeia) of the 24 municipalities of its original range. The exhaustive survey by Kierulff (1993a,b; Kierulff and Procópio de Oliveira 1996; Kierulff and Rylands,2003) which covered the entire range of the species during 18 months between 1990 and 1992, showed that they remain in only 104.5 km² of forests in three regions: 1) near the coast (the Centro Hípico de Cabo Frio, with an estimated 29 individuals, and Campos Novos, with an estimated 36 individuals); 2) the Poço das Antas Biological Reserve and adjacent forests (with an estimated 360 individuals); and 3) on the hillsides of the Serra do Mar (with an estimated 74 individuals), there largely restricted to lowland forest patches. A further nine localities contained 12 isolated groups, totaling 60 individuals. These subpopulations were registered in just four of the municipalities reported by Coimbra-Filho (1969): Silva Jardim, Cabo Frio, Saquarema, and Aruarama, the latter two, however, maintaining only a single group each (Kierulff 1993a).

Burity et al. (2007) reported the occurrence of L. rosalia in the municipality of Duque de Caxias, near the Rio Taquara, in the Taquara Municipal Natural Park (19,000 ha), Rio de Janeiro, a westward extension of its current known range.

In 2003, the species was downlisted from Critically Endangered to Endangered, as a result of nearly thirty years of conservation efforts, involving numerous institutions, through the Golden Lion Tamarin Conservation Program (GLTCP) of the National Zoological park, Smithsonian Institution, Washington, DC, and the Associação Mico-Leao-Dourado, Rio de Janeiro. Conservation efforts have included the establishment of a new population through translocation of 47 individuals in six groups, each isolated and evidently otherwise doomed in tiny isolated forests elsewhere, to a new protected area, the União Biological Reserve. Currently, about one-third of the wild population are descendants of a reintroduction programme. The re-introduction of captive-born Golden Lion Tamarins has contributed significantly not only to the numbers of living in the wild, but also to the protection 3,100 ha of forests within their range (Beck et al. 1986, 1991, 1994; Stoinski et al. 1997; Beck and Martins 1999, 2001).

Early estimates of population size ranged from 200-600 (Coimbra-Filho 1969; Coimbra-Filho and Mittermeier 1973, 1977), but it was only in 1991-1992 that a full and thorough census was carried out by Kierulff (1993a,b; Kierulff and Procópio de Oliveira 1996). Not including the population in the Poço das Antas Biological Reserve, the total number of individuals estimated was 272 in 55 groups. They were divided amongst 14 forests - four main subpopulations with six or more groups each and 12 groups isolated in 10 forest fragments each of 200 ha or less in area. The total area of forest containing Golden Lion Tamarins was 104.5 km². The majority of groups (29) were located in the municipality of Silva Jardim (53%), 24 groups were located in Cabo Frio (43%), and one group each were found in the municipalities of Saquarema and one in Araruama. At the time, the Poço das Antas Biological Reserve was known to harbor about 290 lion tamarins (Kierulff 1993a), giving a total population of 562 (range 470-631), close to the estimate of Coimbra-Filho in 1969.

During Kierulff's (1993) census, the population of re-introduced lion tamarins was 118 individuals, but by December 2000, the number had risen to 359 (Kierulff et al. 2002a,b). A translocation programme, begun in 1994, established a new and thriving population in the União Biological Reserve, with six introduced groups resulting in a population of over 120 lion tamarins in the Reserve by mid-2001 (Kierulff et al. 2002a). The forests targeted for re-introduction are now believed to be at carrying capacity, and Kierulff and Procópio de Oliveira (1996) estimated that the União Biological Reserve (at 2,400 ha the second largest single block of lowland forest in the state, after the marginally larger Poço das Antas Biological Reserve with 2,760 ha of forest) can hold no more than about 158 lion tamarins (33 groups).

Since 1997, the numbers in the Poço das Antas Biological Reserve have been declining due to predation, and only 220 lion tamarins were recorded in December 2000 (see Franklin and Dietz 2001).

The current estimate of L. rosalia in the wild is now over 1,000. There are only very few forests available for further expansion of the population: Kierulff and Procópio de Oliveira (1996) identified a further four areas (two forest blocks, Rio Vermelho with 9 km², and the Morro de São João with 16 km², and two areas of fragmented forests, one of 16 km² along the BR101 at Gaviões and the other of 12 km² bordering the municipalities of Casimiro de Abreu and Silva Jardim) totalling 7,500 ha which could hold a further 500 lion tamarins (about 100 groups). Occupying all the habitat available, the Golden Lion Tamarin population as a whole would still remain below the minimum viable of 2,000 argued by Seal et al. (1991) and Ballou et al. (1998). Metapopulation management and reforestation are key strategies for the continued survival of this species in the wild (Kierulff 1993a; Kierulff and Procópio de Oliveira 1996).

An inhabitant of lowland seasonal rain forest of the Atlantic coast of Brazil, with an average annual rainfall of around 1,500 mm a year (Rylands 1993). Golden lion tamarins are an adaptable species well able to live in degraded and secondary forests, depending only on sufficient year round food sources and foraging sites, along with the tree holes they use as sleeping sites (see Coimbra-Filho 1969, 1976; Coimbra-Filho and Mittermeier 1973).

Marmosets and tamarins are distinguished from the other monkeys of the New World by their small size, modified claws rather than nails on all digits except the big toe, the presence of two as opposed to three molar teeth in either side of each jaw, and by the occurrence of twin births. They eat fruits, flowers, nectar, plant exudates (gums) and animal prey (including frogs, snails, lizards, spiders and insects).

Kierulff et al. (2002a) provide a comprehensive review of the behavioural ecology of the lion tamarins. They differ from other callitrichids in having long fingers and hands, which allow them to forage for prey efficiently in nooks and crannies and in epiphytic tank bromeliads. Lion tamarins live in extended family groups of usually 4 to 8 individuals. For L. rosalia, Dietz and Kleiman (1986) recorded a mean group size of 5.8 (range 3-11, n=21) at the Poço das Antas Biological Reserve. Generally, only one female per group breeds during a particular breeding season. They breed once a year. The groups defend home ranges of 40 to more than 100 ha (the size depending on availability and distribution of foods and second-growth patches). At the Poço das Antas Biological Reserve, L. rosalia groups use home ranges that average 45 ±16 ha (range 21-73 ha) (Dietz et al. 1997). At the União Biological Reserve, home ranges average 150 ±72 ha (range 65-229 ha) (Kierulff 2000).

In the past, major threats included forest loss and fragmentation along with a capture for pets and trade. Today, the main factor is reduced numbers and limited possibilities for growth in the few fragmented and degraded forests that remain in their restricted range.

Deforestation in the state of Rio de Janeiro began in the 16th Century, with successive cycles of development supporting sugar cane plantations, coffee plantations, and in the last century particularly cattle breeding, besides persistent logging, charcoal production, and clearing for urbanization. The state is one of the most populous regions of Brazil, and today L. rosalia is limited to some few and isolated forest patches. Approximately 20% of the original range of L. rosalia is still forested, but 60% of this total is comprised of patches of 1,000 ha or less, 96% of which are less than 100 ha. The average size of the forest patches is 35 ha: smaller than the home range of a single lion tamarin group (Kierulff and Procópio de Oliveira 1996). Fires, set by cattle farmers adjacent to the remaining forest patches in the region, are a constant threat.

A study by Dietz et al. (2000) examined inbreeding depression in small (50 or less) isolated populations of L. rosalia. They concluded that it reduced probability of long-term survival by about one-third.

Included on the Brazilian Official List of Species Threatened with Extinction (Lista Oficial de Espécies Brasileiras Ameaçadas de Extinção, Edict No. 1.522/19th December 1989, see Bernardes et al. 1990; Fonseca et al. 1994), and likewise on the regional threatened species list of the state of Rio de Janeiro (Bergallo et al. 2000). It is listed on Appendix I of CITES.

The first conservation initiatives for Leontopithecus rosalia began with field surveys and initiation of a breeding programme for the species by Adelmar Coimbra-Fillho and Alceo Magnanani in the late 1960s (Coimbra-Filho and Magananini 1972; Magnanini and Coimbra-Filho 1972; Coimbra-Filho 1976a,b). Kleiman (1972) set up an international breeeding programme and studbook for the captive populations in 1972, and initiated the The Golden Lion Tamarin Conservation Program (GLTCP) of the National Zoological Park, Smithsonian Institution, in 1983. The GLTCP is still active and includes field research, reintroduction, environmental education, and habitat restoration programmes, centered on the Poço das Antas Biological Reserve, created in 1972 in Rio de Janeiro (Magnanini 1978).

There is active management of the Poço das Antas and União Biological Reserves, and a stable, managed population in captivity maintained at about 490 animals. However, there is little room for expansion for the population, considering the extreme fragmentation and reduced forest cover within its range. Current and future conservation efforts are attacking this problem with reforestation and the establishment of corridors.

There is an International Committee for the Conservation and Management of lion Tamarins, set up in 1990 by the Brazilian Government (Instituto Chico Mendes de Conservação da Biodiversidade of the Ministry of the Environment) (see Rambaldi et al. 2002).